Final answer:
The least horizontal and vertical extent can be exemplified by coral reefs, which occupy a small area within a latitude/longitude cell, as well as the least common gases in the Earth's atmosphere, amounting to 0.037680%.
Step-by-step explanation:
When considering the question of what encompasses the least horizontal and vertical extent, it's important to look at various geological and geographical formations to understand how they occupy space.
For instance, coral reefs may cover a relatively small area in terms of horizontal and vertical extent compared to other geographic features. They occupy limited space within a 1-degree latitude/longitude cell and do not extend very far above the sea floor or horizontally across the ocean bed. Similarly, when assessing atmospheric components, we can see that certain gases are minimal in quantity.
For example, the least common gases in the Earth's atmosphere, represented by the lower pie, account for a mere 0.037680% of atmospheric composition. Other concepts related to horizontal and vertical extent involve art and literature, where the terms can describe physical dimensions or metaphorically represent other ideas, as seen in interpretations of artistic works like Goya's paintings or in descriptions of the imagery in literature.